Thermostatic regulator



Jan. 1, 1957 J. E. FULLER, JR 2,776,354

THERMOSTATIC REGULATOR Filed Jan. 4, 1954 INVENTOR. JoH/v E. FULLER, J2.

Arr-o2 NEY United States Patent Q 'rnEnMos'rArrc REGULATOR John Emory Fuller, Jr., Montgomery County, Md: as-

signor to American instrument Company, inc, Silver Spring, Md.

Application January 4, 1954, Serial No. 401,791

Claims. (Cl. 2llil-141) This invention relates to thermostats, and more particularly to a thermostat of the adjustable type.

A main object of the invention is to provide a novel and improved adjustable thermostat of the liquid contact type, which is simple in construction, which is easy to adjust, and which is reliable in operation.

A further object of the invention is to provide an improved adjustable thermostat which is inexpensive to manufacture, which is rugged in construction, and which may be accurately adjusted to close its contacts at a predetermined temperature.

A still further object of the invention is to provide an improved adjustable thermostat of the mercury contact type, which involves only a few parts, which is stable in operation, and wherein the adjustable elements thereof are protected against mechanical damage and from airborne dust, dirt, moisture, and the like.

Further objec.s and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

Figure 1 is a side elevational view, partly in vertical cross-section, of an improved adjustable thermostat constructed in accordance with the present invention.

Figure 2 is an enlarged vertical cross-sectional detail view taken on line 22 of Figure 1.

Figure 3 is a horizontal plan view taken on line 33 of Figure 2.

Figure 4 is an enlarged fragmentary elevational view of a portion of the neck of the thermostat of Figures 1 to 3.

Referring to the drawings, 11 generally designates a typical embodiment of my improved thermostat. The thermostat 11 comprises a main bulb 12 made of glass, or other suitable material, which is filled with mercury 13. At its top end, the bulb 12 is formed with a tubular neck is having the axial bore 15. At its upper portion the bore is reduced in diameter, as shown at 16. A contact wire 17 is sealed in the neck 14 and has its in nor end portion projecting into the reduced bore 16, as is clearly shown in Figure 2. I

The top of neck 14 is formed with a bulb 18 of substantial volume terminating at its top end in the tubular nozzle portion 19 of substantial length. Designated at 29 is a contact wire which extends loosely through the nozzle portion 19, downwardly through the bulb it and into the bore 16, terminating a short distance above the contact wire 17, said distance being adjustable in a manner presently to be described.

The Wire 20 is sealingly secured in and extends through a cap member 21, of glass or other suitable material. Cap member ii is provided with :a flanged skirt 22 which is sealingly secured in the top end of a flexible bellows 23, said bellows being made of plastic material of suitable fiexibility, or of other suitable flexible material. The top portion of neck 14 is formed with an annular flanged rim 24 which is sealingly secured in the lower end or" the bellows 23.

idatentecl Jan. 1, 1957 As will be seen from Figure 2, a substantially annular overflow chamber 25 is thus defined at the top end of neck 14 around the bulb 18.

Designated at 26 is a generally cylindrical housing which Surrounds the bellows 23 and cap 21, and which has a bottom Wall 27 receiving and rigidly secured to the lower end of bellows 23 and the flanged rim 24, as shown in Figure 2. Rotatably mounted in the top wall 28 of the housing 26 in axial alignment with the cap member 21 is the internally threaded bushing 29, said bushing having the knurled top annular flange 30 overlying the top wall 28 and the annular bottom flange 31 underlying said top wall. Designated at 32 is a cylindrical block which is formed with a bottom recess interfitting with and receiving the top portion of cap member 21. Axially secured on the block 32 is the threaded stud 33 which is threadedly engaged with the internal threads of bushing 23. Secured in the block 32 are diametrically opposed guide pins 34, 34 which are slidably received in vertical slots 35, 35' formed in the wall of housing 26.

The contact wire 2d extends through a bore 36 formed in block 32 and through a vertical slot 37 in the upper portion of the wall of housing 26, as shown, whereby said wire 2*!) is free to move vertically as the block 32 and cap member 21 are vertically adjusted. The block 32 and stud 35 are held against rotation by the engagement of the pins 3 34 in the slots 35, 35.

The distance between the lower end of wire 24) and the stationary contact wire i7 may be adjusted by rotating the knurled bushing 29. The resilient bellows 23 is normally under sufficient compression to always exert an upward force on the cap member 21, keeping said cap member continuously in engagement with the block 32 over the entire range of vertical adjustment or" the cap member. Rotation of knurled bushing 29 thus serves to move the stud 33 and block 32 vertically, whereby the cap member 21 follows such movement. Since the wire as is rigidly secured to said cap memher, the lower end of said wire in bore 16 may be vertically adjusted to a desired spacing relative to the stationary contact wire 17.

The lower contact wire l; is located at a point on neck 14 corresponding to a first temperature value. The lower end of wire as may be adjusted to a position corresponding to a second temperature value, above said first temperature value by a predetermined difference. When the temperature reaches said second temperature value, the column of mercury 23 in bore 16 electrically connects contact wire 17 to contact wire as and thus closes the circuit controlled by the thermostat.

A substantial excess of temperature rise above said second temperature value causes the mercury to rise into the bulb is, which is large enough to take care of a substantial quantity of mercury without permitting overflow. Should the temperature rise to a sufiicient value to cause overflow through the nozzle 19, the excess mercury will be received in the overflow chamber 25. The mercury in chamber 25 may be returned to the bulb 18 by inverting the thermostat and heating the cap member 21 to drive the mercury back into the bulb 18.

As shown in Figure 3, the top wall 28 of housing 26 may be provided with a calibrated circular scale 38 and the top flange 3d may be inscribed with an index pointer 3%, whereby the second temperature value (at which closure of the controlled circuit occurs) may be accurately set by rotating the bushing 29 until the pointer 39 is located at a position corresponding to said second tem perature value.

The neck 14 of the thermostat is preferably provided with a thermometer scale 40, as shown in Figure 4, whereby the temperature value associated with the lower end of wire 2t) may be roughly observed. This may be employed to make a coarse adjustment of wire 2! A fine adjustment may be made by means of index pointer 39 and scale 38.

While a specific embodiment of an improved adjustable thermostat has been disclosed in the foregoing description, it Will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

l. A thermostat of the liquid contact type comprising a vessel having a main bulb portion, a tube portion, connected at one end to said main bulb portion, an auxiliary bulb portion connected to the other end of said tube portion, a flexible portion secured to said other end of said tube portion and containing said auxiliary bulb portion, said flexible portion being arranged in axial alignment with said tube portion, a conductive liquid within said bulb and tube portions, 21 first contact member in said vessel, a second contact member in said flexible portion and extending through said auxiliary bulb portion into said tube portion, and means arranged axially with respect to said flexible portion and tube portion for applying axial force on said flexible portion to adjust the distance between said first and second contact members, said auxiliary bulb portion being open at its end to at times allow liquid from said tube portion to overflow into said flexible portion.

2. A thermostat of the liquid contact type comprising a vessel having a main bulb portion, a tube portion, connected at one end to said main bulb portion, an auxiliary bulb portion connected to the other end of said tube portion, a flexible portion secured to said other end of said tube portion and containing said auxiliary bulb portion, said flexible portion being arranged in axial alignment with said tube portion, a conductive liquid within said bulb and tube portions, a rigid member on the end of said flexible portion, a first contact member in said vessel, :1 second contact member secured to said rigid member, extending through said flexible portion and extending through said auxiliary bulb portion into said tube portion, and means arranged axially with respect to said flexible portion and tube portion for applying axial force on said rigid member to adjust the distance between said first and second contact members, said auxiliary bulb portion being open at its end to at times allow liquid from said tube portion to overflow into said flexible portion.

3. A thermostat of the liquid contact type comprising a vessel having a main bulb portion, a tube portion, connected at one end to said main bulb portion, an auxiliary bulb portion connected to the other end of said tube portion, a flexible portion secured to said other end of said tube portion and containing said auxiliary bulb portion, said flexible portion being arranged in axial alignment With said tube portion, a conductive liquid Within said bulb and tube portions, a rigid member on the end of said flexible portion, a first contact member in said vessel, a second contact member secured to said rigid member, extending through said flexible portion and extending through said auxiliary bulb portion into said tube portion, a block element engaging said rigid member, a support secured to said tube portion and extending over said block element, a bushing element rotatably mounted on said support in axial alignment with said tube portion, and means on said block element engaging said bushing element and being movable axially of the tube portion responsive to rotation of said bushing element for applying axial force on said rigid member to adjust the distance between said first and second contact members, said auxiliary bulb portion being open at its end to at times allow liquid from said tube portion to overflow into said flexible portion.

4. A thermostat of the liquid contact type comprising a vessel having a main bulb portion, a tube portion, connected at one end to said main bulb portion, an auxiliary bulb portion connected to the other end of said tube portion, a flexible portion secured to said other end of said tube portion and containing said auxiliary bulb portion, said flexible portion being arranged in axial alignment with said tube portion, a conducti e liquid within said bulb and tube portions, a rigid memher on the end of said flexible portion, a first contact member in said vessel, a second contact member secured to said rigid member, extending through said flexible portion and extending through said auxiliary bulb portion into said tube portion, a block element engaging said rigid member, a housing secured to said tube portion, said housing surrounding said flexible portion and extending over said block element, a bushing element rotatably mounted on said housing in axial alignment with said tube portion, and means on said block element engaging said bushing element and being movable axially responsive to rotation of said bushing element for applying axial force on said rigid member to adjust the distance between said first and second contact members, said auxiliary bulb portion being open at its end to at times allow liquid from said tube portion to overflow into said flexible portion.

5. A thermostat of the liquid contact type comprising a vessel having a main bulb portion, a tube portion, connected at one end to said main bulb portion, an auxiliary bulb portion connected to the other end of said tube portion, a flexible portion secured to said other end of said tube portion and containing said auxiliary bulb portion, said flexible portion being arranged in axial alignment with said tube portion, a conductive liquid within said bulb and tube portions, a rigid member on the end of said flexible portion, a first contact member in said vessel, a second contact member secured to said rigid member, extending through said flexible portion and extending through said auxiliary bulb portion into said tube portion, a block element engaging said rigid member, a housing secured to said tube portion, said housing surrounding said flexible portion and extending over said block element, a bushing element rotatably mounted on said housing in axial alignment with said tube portion, means on said block clement engaging said housing and limiting rotation of said block element, and a stud member on said block element threadedly engaging said bushing element and being movable axially of the tube portion responsive to rotation of said bushing element for applying axial force on said rigid member to adjust the distance between said first and second contact members, said auxiliary bulb portion being open at its end to at times allow liquid from said tube portion to overflow into said flexible portion.

References Cited in the file of this patent UNITED STATES PATENTS 

